Add tests for install-plugins.sh

Use bats-assert and bats-support for testing
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..6f8a2f8
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,6 @@
+[submodule "tests/test_helper/bats-support"]
+	path = tests/test_helper/bats-support
+	url = https://github.com/ztombol/bats-support
+[submodule "tests/test_helper/bats-assert"]
+	path = tests/test_helper/bats-assert
+	url = https://github.com/ztombol/bats-assert
diff --git a/tests/install-plugins/Dockerfile b/tests/install-plugins/Dockerfile
index 72d28f7..ad1db16 100644
--- a/tests/install-plugins/Dockerfile
+++ b/tests/install-plugins/Dockerfile
@@ -1,3 +1,3 @@
 FROM bats-jenkins
 
-RUN /usr/local/bin/install-plugins.sh maven-plugin@2.7.1
+RUN /usr/local/bin/install-plugins.sh maven-plugin:2.7.1
diff --git a/tests/test_helper/bats-assert b/tests/test_helper/bats-assert
new file mode 160000
index 0000000..9f88b42
--- /dev/null
+++ b/tests/test_helper/bats-assert
@@ -0,0 +1 @@
+Subproject commit 9f88b4207da750093baabc4e3f41bf68f0dd3630
diff --git a/tests/test_helper/bats-support b/tests/test_helper/bats-support
new file mode 160000
index 0000000..d0a1318
--- /dev/null
+++ b/tests/test_helper/bats-support
@@ -0,0 +1 @@
+Subproject commit d0a131831c487a1f1141e76d3ab386c89642cdff
diff --git a/tests/tests.bats b/tests/tests.bats
index 01f42fe..65ecf74 100644
--- a/tests/tests.bats
+++ b/tests/tests.bats
@@ -3,6 +3,8 @@
 SUT_IMAGE=bats-jenkins
 SUT_CONTAINER=bats-jenkins
 
+load 'test_helper/bats-support/load'
+load 'test_helper/bats-assert/load'
 load test_helpers
 
 @test "build image" {
@@ -49,9 +51,24 @@
       bash -c "curl -fsSL --user \"admin:$(get_jenkins_password)\" $(get_jenkins_url)/systemInfo | sed 's/<\/tr>/<\/tr>\'$'\n/g' | grep '<td class=\"pane\">user.timezone</td>' | sed -e '${sed_expr}'"
 }
 
-@test "plugins are installed" {
+@test "plugins are installed with plugins.sh" {
   docker build -t $SUT_IMAGE-plugins $BATS_TEST_DIRNAME/plugins
-  assert "maven-plugin.jpi maven-plugin.jpi.pinned" docker run -ti --rm $SUT_IMAGE-plugins ls /var/jenkins_home/plugins | sed -e 's/  / /'
+  assert_success
+  # replace DOS line endings \r\n
+  run bash -c "docker run -ti --rm $SUT_IMAGE-plugins ls -1 /var/jenkins_home/plugins | tr -d '\r'"
+  assert_success
+  assert_line 'maven-plugin.jpi'
+  assert_line 'maven-plugin.jpi.pinned'
+}
+
+@test "plugins are installed with install-plugins.sh" {
+  run docker build -t $SUT_IMAGE-install-plugins $BATS_TEST_DIRNAME/install-plugins
+  assert_success
+  # replace DOS line endings \r\n
+  run bash -c "docker run -ti --rm $SUT_IMAGE-plugins ls -1 /var/jenkins_home/plugins | tr -d '\r'"
+  assert_success
+  assert_line 'maven-plugin.jpi'
+  assert_line 'maven-plugin.jpi.pinned'
 }
 
 @test "clean test containers" {